<template>
    <el-color-picker v-model="theme" :predefine="['#409EFF', '#1890ff', '#304156','#212121','#11a983', '#13c2c2', '#6959CD', '#f5222d']" class="theme-picker" popper-class="theme-picker-dropdown" />
</template>

<script lang="ts">
import { Component, Prop, Vue, Watch } from "vue-property-decorator";
import { SettingsModule } from "@/store/modules/settings";
import { style as variables } from "@/config/index";

const version = require("element-ui/package.json").version; // element-ui version from node_modules
// const ORIGINAL_THEME = "#409EFF"; // default color

@Component({
    name: "ThemePicker"
})
export default class extends Vue {
    private chalk = ""; // The content of theme-chalk css
    private theme = "";

    get defaultTheme() {
        return SettingsModule.theme;
    }

    @Watch("defaultTheme", { immediate: true })
    private onDefaultThemeChange(value: string) {
        this.theme = value;
    }

    @Watch("theme")
    private async onThemeChange(value: string) {
        if (!value) return;
        const oldValue = this.chalk ? this.theme : variables.menuActiveText;
        const themeCluster = this.getThemeCluster(value.replace("#", ""));
        const originalCluster = this.getThemeCluster(oldValue.replace("#", ""));
        const message = this.$message({
            message: "  Compiling the theme",
            customClass: "theme-message",
            type: "success",
            duration: 0,
            iconClass: "el-icon-loading"
        });

        if (!this.chalk) {
            const url = `https://unpkg.com/element-ui@${version}/lib/theme-chalk/index.css`;
            await this.getCSSString(url, "chalk");
        }

        const getHandler = (variable: string, id: string) => {
            return () => {
                const originalCluster = this.getThemeCluster(
                    variables.menuActiveText.replace("#", "")
                );
                const newStyle = this.updateStyle(
                    (this as any)[variable],
                    originalCluster,
                    themeCluster
                );

                let styleTag = document.getElementById(id);
                if (!styleTag) {
                    styleTag = document.createElement("style");
                    styleTag.setAttribute("id", id);
                    document.head.appendChild(styleTag);
                }
                styleTag.innerText = newStyle;
            };
        };
        const chalkHandler = getHandler("chalk", "chalk-style");
        chalkHandler();

        let styles: HTMLElement[] = [].slice.call(
            document.querySelectorAll("style")
        );
        styles = styles.filter(style => {
            const text = style.innerText;
            return (
                new RegExp(oldValue, "i").test(text) &&
                !/Chalk Variables/.test(text)
            );
        });
        styles.forEach(style => {
            const { innerText } = style;
            if (typeof innerText !== "string") return;
            style.innerText = this.updateStyle(
                innerText,
                originalCluster,
                themeCluster
            );
        });

        this.$emit("change", value);
        message.close();
    }

    private updateStyle(
        style: string,
        oldCluster: string[],
        newCluster: string[]
    ) {
        let newStyle = style;
        oldCluster.forEach((color, index) => {
            newStyle = newStyle.replace(
                new RegExp(color, "ig"),
                newCluster[index]
            );
        });
        return newStyle;
    }

    private getCSSString(url: string, variable: string) {
        return new Promise(resolve => {
            const xhr = new XMLHttpRequest();
            xhr.onreadystatechange = () => {
                if (xhr.readyState === 4 && xhr.status === 200) {
                    (this as any)[variable] = xhr.responseText.replace(
                        /@font-face{[^}]+}/,
                        ""
                    );
                    resolve();
                }
            };
            xhr.open("GET", url);
            xhr.send();
        });
    }

    private getThemeCluster(theme: string) {
        const tintColor = (color: string, tint: number) => {
            let red = parseInt(color.slice(0, 2), 16);
            let green = parseInt(color.slice(2, 4), 16);
            let blue = parseInt(color.slice(4, 6), 16);
            if (tint === 0) {
                // when primary color is in its rgb space
                return [red, green, blue].join(",");
            } else {
                red += Math.round(tint * (255 - red));
                green += Math.round(tint * (255 - green));
                blue += Math.round(tint * (255 - blue));
                return `#${red.toString(16)}${green.toString(
                    16
                )}${blue.toString(16)}`;
            }
        };

        const shadeColor = (color: string, shade: number) => {
            let red = parseInt(color.slice(0, 2), 16);
            let green = parseInt(color.slice(2, 4), 16);
            let blue = parseInt(color.slice(4, 6), 16);
            red = Math.round((1 - shade) * red);
            green = Math.round((1 - shade) * green);
            blue = Math.round((1 - shade) * blue);
            return `#${red.toString(16)}${green.toString(16)}${blue.toString(
                16
            )}`;
        };

        const clusters = [theme];
        for (let i = 0; i <= 9; i++) {
            clusters.push(tintColor(theme, Number((i / 10).toFixed(2))));
        }
        clusters.push(shadeColor(theme, 0.1));
        return clusters;
    }
}
</script>

<style lang="less">
.theme-message,
.theme-picker-dropdown {
    z-index: 99999 !important;
}

.theme-picker .el-color-picker__trigger {
    height: 26px !important;
    width: 26px !important;
    padding: 2px;
}

.theme-picker-dropdown .el-color-dropdown__link-btn {
    display: none;
}
</style>
